Place pineapple and water in sauce pan. Heat over low flame. Slowly add sugar while stirring. When sugar has dissolved, slowly add the vinegar and the lemon juice while stirring. Add corn starch slurry and stir while heating. Bring to a boil. Stir constantly until thickened. Add food coloring (a couple drops at first and then adjust until you have the red color you like) and stir well to mix. Continue to heat and stir until almost a syrup. Remove from heat and set aside. You will be judging the thickness of the sauce while it is hot. It will thicken considerably when it is set aside and cools. Later, when added to the vegetables, the moisture from the vegetables will thin the sauce quite a bit.